Cyclic combustion gas generator



Nov. 7, 1950 H. BOHUSLAV ,5 ,3

cycuc comausnou GAS QENERATOR I Filed May 2, 1945 I 4 Sheetts-Sheet 1 INVENTOR.

1950 H. BOHUSLAV 2,529,325

CYCLIC COMBUSTION GAS GENERATOR I Filed May 2, 1945 4 Sheets-Sheet 2 I 1 l g 0 I 7/ I I l I I I 1 1' I 1 x I w 1 4' I 4 I T; *1 I IN V EN TOR.

OTWQS 1950 H. QBOHUSLAV 2,529,325

CYCLIC COMBUSTION GAS GENERATOR Filed May 2, 1945 4 Sheet s-Sheet s H. BOHUSLAV CYCLIC COMBUSTION GAS GENERATOR Nov. 7, 1950 4 Sheets-Sheet 4 Filed May 2, 1945 2 6 6 glut gin.

Patented Nov. 7, 1950 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to improvements in method and apparatus for generating fluid pressure, of the type in which fuel is burnt in constant volume explosion chambers.

One of the objects of this invention is to provide an apparatus and method of this type by means of which high fluid pressures can be produced. Another object is to provide an improved method and apparatus of high efliciency for com pressing air and other gases. A further object is to provide apparatus and method of this kind in which the explosion or combustion chambers are highly supercharged before ignition takes place. Another object is to provide an apparatus and method of this type including a plurality of explosion or combustion chambers connected so that part of the pressure developed in each chamher is used for pre-compressing the charge or working medium in another chamber before ignition takes place in the other chamber. A furtheir object of this invention is to provide an apparatus and method of this kind in which the compressed fluid delivered by the apparatus is at a materially lower temperature than that resulting'from the combustion of the fuel in a combustion chamber.

Another object of this invention is to provide an apparatus of this type in which the combustion chambers are in the form of elongated tubes. A further object is to provide an apparatus of this type in which the combustion chambers can be more readily scavenged of burnt gases after each explosion. A further object is to provide a combustion chamber which is so constructed that the ballistic force of the exhaust may be used to draw fresh air into the combustion chamber.

A further object of this invention is to provide an apparatus of this type in which the tubular combustion chambers are of loop shape so that the inlet and discharge of compressed fluid may be more readily controlled by valves. Other objects and advantages of this invention will appear from the following description and claims.

In the accompanying drawings:

Fig. l is a view, partly sectional and partly diagrammatic, of an apparatus for generating fluid pressure embodying this invention.

Fig. 2 is a similar view showing a modified valve control for the apparatus.

Fig. 3 is a diagram showing approximately the pressure conditions existing in a pair of combustion chambers or tubes during a cycle of operation of my improved apparatus and method.

Fig. 4 is a fragmentary view of an apparatus similar to that shown in Fig. 1, but adapted for operation with solid fuel.

In the particular embodiment of my invention illustrated in Fig. 1, l and 8 represent a pair of combustion or explosion chambers. These chambers are of elongated tubular form, and of a length many times greater than their diameters. The tubular chambers may be straight or of any other desired shape, but preferably for sake of convenience, they are of approximately U or loop shape, so that the inlet end 9 of each tube or combustion chamber is located adjacent to the discharge end I!) thereof. These combustion chambers may be of slightly larger diameters at their inlet and discharge ends, but are preferably of substantially uniform diameter throughout the major portions of their lengths, and are provided near their inlet ends with fuel admission jets or nozzles I I and with suitable means for igniting a combustible mixture, such for example as a spark plug l2. Other means for introducing fuel into the combustion chambers and for igniting the same may, of course, be employed. For example, if operating at high compression pressures, auto ignition would take place as the fuel is being injected, as in a compression ignition engine, commonly known as the Diesel engine, but in such case, spark plugs or other igniting means may be used for starting and warming up.

Each tube or combustion chamber is provided with air inlet valves 1'3 and I4 and exhaust valves I5 and I6, and for reasons hereinafter more fully explained, the inlet and discharge ports controlled by these valves are preferably approximately as large as or larger than the cross sectional area of the main or body portions of the tubular combustion chambers.

One of the features of this invention is that the tubular combustion chambers are connected with each other in such a manner that a part of the compressed fluid in each tube is discharged into the discharge end of the other tube before ignition takes place in the other tube, so that higher pressures may be developed by means of the apparatus and method embodying this invention. For this purpose, the discharge end of the two tubes 1 and 8 may be connected by any suitable means, for example, as in the construction shown in Fig. 1, by means of a passage or compressed fluid manifold ll formed by a wall I8 which may be formed integral with the two tubular com bustion chambers, and a valve supporting base member I9, in which the inlet and discharge valves are mounted. The passage or manifold l1 connects with passages or ducts 20 and 2| formed in the valve supporting base member IS. The ducts 20 terminate in a port controlled b the exhaust valve l5 of the tube 1 and the other duct 2| terminates in a port controlled by the exhaust valve I8 01' the tube 8. Consequently, when the valve It is opened after explosion of the combustible mixture in tube I and the exhaust valve I8 of tube 8 is also opened, some of the pressure generated in the tube 1 will be transmitted into the tube 8 before ignition therein and vice versa, after ignition in the tube 8, when the exhaust valves I and iii are opened, compressed gas will flow through the passage I'I into the tube 1 and thus create a pressure in the tube I before ignition takes place therein, this increase in pressure of the tubes being herein referred to as pre-compressing.

The inlet valves l3 and I4 are respectively connected with air inlets 23 and 24 which connect with suitable passages in the base I9 leading to the inlet valves. These air inlet tubes may be open to the atmosphere at their outer ends or they may be connected to a blower or pump (not shown) if it is desired to supply air under pressure to the tubes, in accordance with well known supercharging practice used in connection with internal combustion engines.

25 represents a valve for controlling the discharge of compressed fluid from the apparatus, this valve controlling a port formed in the base I9 and terminating in the passage l1 and connecting with a discharge pipe or tube 21 which may lead to any suitable device to which the compressed gas is to be supplied and which is designated by the reference character 28. This may be a receiver in which the compressed gas may be stored or it may be a turbine or other motor actuated by compressed fluid, and the term receiver is herein employed to designate either a container for compressed gas or any other machine or apparatus to which compressed gas is delivered.

represents an exhaust valve which controls a port connected through a passage in the base I9 with an exhaust duct 3| which may lead to the atmosphere or to any suitable device 32, which may, for example, be a muffler or it may be a low pressure turbine which may be actuated by the pressure of the exhaust gas from the apparatus. Such low pressure turbine may, for example, be used to drive an air compressor or blower for admitting air under pressure into the air inlet pipes 23 and 24. 33 represents a tail pipe through which the exhaust from the device 32 is discharged to the atmosphere and if the device 28 which is hereinafter referred to as a receiver is in the form of a turbine or motor, the exhaust from the same may be conducted through a branch pipe 34 leading through the tail pipe 33.

, The various valves may be actuated by means of a cam shaft 31 having cams 38 thereon, the cams being arranged to actuate the valves in any suitable manner, for example, by contact with the valve tappets 39, and the tappets may be guided for movement lengthwise in suitable bearings formed in a cover plate 40 which may in turn be suitably secured to upwardly extending outer walls or flanges 4| of the base I9. The valves may be timed in the usual manner by means of the cams and tappets, and the cam shaft may be rotated by any suitable or desired driving means. In the construction illustrated by way of example an electric motor 44 is employed for driving an upright shaft on which a bevel gear 45 is secured which meshes with a bevel gear 45a on the cam shaft 31. The upright shaft on which the beveled gear 45 is mountof tubes or ducts 48 leading to' the fuel injectiorhnozzles II and the distributor being connectedby means of wires 50 to the spark plugs I2. Any other suitable means for actuating the valves, the fuel pump and the distributor may, of course, be employed.

In starting the apparatus described, assuming that tubes 1 and 8 contain air and the inlet and discharge valves I3 and I5 are closed, fuel is admitted through the nozzle II and ignited in the inlet end 9 of the tube I. This tube is relatively long so that it may contain a considerable amount of air in excess of that required to support combustion, and consequently, when the fuel becomes ignited, an increase in pressure is developed in the tube 1. Immediately after combustion, the exhaust valves I5 and iii of the tubes 1 and 8 are opened so that some of the pressure generated in the tube I is transmitted through the passage or manifold I'I into the discharge end of the tube 8, thus precompressing the air within the tube 8. The exhaust valve l6 of tube 8 is then closed while exhaust valve I5 of tube 1 remains open, and valve 25 leading to the tube 21 connected with the receiver is opened, so that another part of the compressed gas from the tube is discharged to the receiver, which as hereinbefore stated may be a storage reservoir, a turbine, or a motor driven by the compressed gas. After the greater part of the gas from the tube I has been discharged, the valve 25 is closed and theexhaust valve 30 is opened, the exhaust valve I5 of the tubal remaining open. A rapid flow of compressed gas from the tube I into the exhaust tube 3i, consequently, results and immediately after this rapid flow has been established, the inlet valve I3 of tube is opened. The rapid movement of the exhaust through the tube I and the discharge pipe 3i results in the forming of a partial vacuum or sub-atmospheric pressure in the tube I due to the ballistic force of the exhaust, or to the momentum of the body of gas flowing in thetubes I, the passage I1 and the discharge or exhaust tube 3|. By proper timing of the air inlet valve I3 so that this valve opens just as the pressure in the tube or chamber I begins to approach the sub-atmospheric, a rush of fresh air from the atmosphere into the tube I takes place, due to the partial vacuum formed in the tube 1 by the ballistic force. By proper proportioning or design of the valves and the tube or combustion chambers, the incoming fresh air may be admitted in sufficient volume to completely displace the products of combustion from the tube I, thus scavenging the tube and cooling the same, and providing an ample supply of air to support combustion of the next charge of fuel admitted to the tube. However, since only a part of the air in the tube I is required for combustion, no harm will result if the quantity of air admitted is not suiiicient to completely fill the tube Wtih fresh air, since burnt gases remaining in the discharge end of the tube will not interfere with the successful operation of the apparatus, since in that case the compressed gas delivered by the apparatus will merely contain a larger percentage of products of combustion and a smaller percentage of air. As soon as the admission of air is completed, the valves I3 and 30 are closed.

In the meantime, combustion has taken place in the other tube 8 which operates on a cycle identical with tube I but one half cycle later. This combustion in tube 8'results in compression of the mixture of air and gas contained therein and the exhaust valve l6 of tube 8 is then opened, thus allowing a part or the compression charge from tube 8 to be admitted to the discharge end of tube 1 through valve l5 which is still open, thus compressing the air or mixture of air and burnt as in the tube 1 prior to ignition of fuel in this tube. This pre-compressing in tube 1 is followed by the quick closing of the exhaust valve l5 and opening of the valve 25 leading to the receiver which in turn is followed by the closing of the valve 25 and the opening of the exhaust valve 30, thus discharging burnt gases from the tube 8. Air inlet valve M is then opened admitting fresh air into tube 8 because of the sub-atmospheric pressure in tube 8 due to the ballistic force of the exhaust. The operations are then repeated and the speed with which they are repeated depends upon the speed of the motor 44 which controls the valve. The speed of this motor may in turn be controlled by means of the usual rheostat 53 or other suitable means.

The energy remaining in the exhaust may be used to more thoroughly scavenge the tubes and to supercharge the tubes. For this purpose, the exhaust may be fed to a low. pressure turbine which in turn drives a blower to supply air to the air inlet pipes 23 and 24 under pressure, to positively force fresh air into the tubes 1 and 8 to thoroughl scavenge the tubes. Due to the intermittent discharge of exhaust gas, the pressure in the combustion chamber tubes and the exhaust duct will be near or below atmospheric pressure at intervals. The inlet valve and exhaust valve would both be open at this interval, so that fresh air can flow through the tube to cool and scavenge it.

I prefer to have the combustion chambers in the form of tubes of substantially uniform diameter, so that when the exhaust valve of a tube is opened, followed immediately by the opening of the inlet valve, the incoming fresh air will displace the burnt gases in the tube with the minimum of turbulence and intermixing of fresh air with the burnt gases. The relatively long tubular combustion chambers also have the advantage that air admitted may be materially in excess of "that required to support combustion, in which case, a part of the compressed gas which is delivered is air. In this manner, excessively high temperatures in the tubes or combustion chambers can be avoided. By making the combustion chambers in the form of tubes and reducing turbulence to a minimum, the tubes offer less resistance to the flow of gases through the same, so that a higher partial vacuum is formed in the tubes due to the ballistic force of the exhaust. In order to reduce to a minimum the resistance to the flow of gas through the tubes, the inlet and discharge valves are made as large as possible and the inlet and discharge ends of the tubes are of somewhat larger cross sectional areas than the remaining portions of the tubes so as to facilitate the flow of gases into and out of the tubes. It is not intended, however, to limit this invention to the particular type of tubular combustion chambers described, since good results .may be obtained by using combustion chambers of other shapes and forms. I prefer to discharge the first portion of the compressed gas from one tube into the other tube for pre-compressing, for the reason that my apparatus, operating at a higher pressure than could be obtained by a single combustion chamber, develops higher temperatures than would be produced in-a single combustion chamher, and these temperatures may be too high for use in a gas turbine. However, by first discharging a part of the compressed gas from any tube into the other tube, the gas at the highest temperature and pressure is used for pro-compressing the charge in the other tube and the resulting reduction in pressure of the gas due to discharging a portion thereof into the other tube, results in a reduction in temperature, so that the second part of the gas can be readily used in a turbine and will have a pressure materially higher than could be produced by means of a single combustion chamber. If desired, however, the intial discharge of gas from a tube may be conducted to a receiver, and the second part of the gas may be supplied to another tube for pre-compressing the charge in the same.

While I have shown the apparatus as including two tubes, it will lie obvious that any number of tubes may be used, provided that each tube is connected to discharge a part of its gas to another tube. Also for a larger capacity, a plurality of tubes arranged in pairs as shown in Fig. 1 may be provided. The tubes may, of course, be materially larger in size in proportion to the valve mechanism than shown in Fig. 1.

In Fig. 3 I have shown diagrammatically the theoretical cycles of operation of the two tubes, the cycle of operation of one tube being shown in a full line and the cycle for the other tube in a broken line. The base represents time and the ordinate or vertical lines represent pressure. At point 5 5, the tube whose cycle is represented by the full line curve has just completed its intake of air and the pre-compressing of the charge in the tube from the other tube is commenced, this resulting in an increase in pressure from to 58 and a corresponding decrease of pressure in the other tube represented by the broken line curve. At about 56 ignition takes place in the full line curve so that the pressure rises, and at the same time discharge of compressed gas to the receiver from the tube represented by the broken line curve takes place, resulting in a decrease in pressure from 62 to 63. Somewhere near the point 51, the compressed gas in tife tube whose cycle is represented by the full line curve is discharged into the other tube, resulting in a rise in the broken line curve for the other tube and a drop in pressure in the full line curve from 51 to 58. At 58 the discharge of compressed gas to the receiver 28 takes place and at about point 59, the valve 25 is closed and the exhaust valve 30 is opened, resulting in a rush of exhaust gas through the combustion tube and the other passages for the exhaust and at point 60 the ballistic force of the exhaust produces a sub-atmospheric pressure in the tube. Consequently, at point 60, the intake valve of the tube is opened, resulting in the scavenging of the tube and the admission of fresh air for the next explosion. The cycle is then repeated from point 55 of the full line curve. From the description of the full line curve on Fig. 3, the

corresponding operations in the broken line curve will be obvious, the two curves being identical as shown but merely being out of phase to the extent necessary to enable the tubes to cooperate with each other as described.

In Fig. 2 I have shown a similar arrangement of two combustion chambers or tubes 10 and H, the operation of which is substantially identical with that of the tubes shown in Fig. 1. In Fig. 2 I have shown a difierent valve mechanism for controlling the flow of,.air and burnt gases. In this construction, 12 represents a valve block or base in which two cylindrical valves I3 and 14 are arranged in cylindrical apertures formed in the base 12. These valves are arranged to slide lengthwise and also to oscillate. Each valve near the lower end thereof has a radially extending pin I5 which has a ball and socket connection with .a crank wheel II, so that during rotation of the wheels the valves are moved in the direction of their lengths and also oscillated about their axes. Since valves of this type are well known in englne construction, they are not herein described or shown in detail. The valve actuating crank wheels are rotatable on shafts or bearings in the base 12, and are connected by a sprocket chain I9 or other suitable means, for simultaneous rotation, and one of the wheels is driven, for example, by another sprocket chain 80, which operates on a sprocket wheel 8I mounted on a shaft 82 on which a fuel pump and a distributor may be mounted. 83 represents a motor for driving the distributor 84 and fuel feed pump 85, for example, through a sprocket chain 86. Any other means for driving the valves, the distributor and the fuel pump may be provided. The distributor 84 is connected by means of wires or suitable conductors to spark plugs or other igniting devices 88 arranged at the inlet ends of the two combustion chambers or tubes I0 and II, and the fuel pump is connected by suitable pipes or ducts to discharge nozzles 89 also leading to the receiving ends of the combustion chambers.

The valve block or base is provided with a plurality of passages controlled by ports or openings formed in the tubular valve members I3 and M. For example, 90 and 9| represent air inlet passages leading to the inlet ends of the combustion tubes and 92 and 93 are passages corresponding to the manifold II shown in Fig. 1. These manifold passages 92 and 93 are connected by means of branch passages 94 and 95 to a central passage 96 leading to a discharge pipe 91 connected to a receiver 98 diagrammatically shown, and which may be either a tank for receiving compressed gases, a turbine, motor or other device to be operated by the compressed gas developed in the apparatus. The valves are provided with suitable openings which connect with the branch passages 94 and 95 in proper time to discharge compressed gases to the receiver. The two manifold passages are also connected by a passage 99 shown in broken lines in Fig. 3 and controlled by suitable ports (not shown) in the valves I3 and I I, for pre-compressing the charge in each tube with compressed gas from the other tube. Another passage I00 is formed in the lower part of the valve block or base 12 and connects with an exhaust or discharge pipe IN, and the manifold passages 92 and 93 are provided with branch passages I02 and I03 which lead to the exhaust passage I00, and which are controlled by suitable ports in the valves I3 and I4.

The arrangement of the ports in the valves is such that the cycles of operation of the two combustion chambers will be the same as in Fig. 1. In the particular positions of the parts shown, the exhaust valve port controlling the branch passage I02 is in open position and the air inlet passage 90 for the tube is also opened so that a supply of fresh air is being supplied to the tube I0, for

example, by the ballistic force of the exhaust passing out through the exhaust pipe IOI. All of the valve ports leading to and from the tube 'II are shown closed so that this tube is ready for combustion of the fuel admitted thereto. Any other suitable or desired arrangement 0 valves for controlling the operation of the combustion chambers as described in connection with Fig. 1 may be employed, and it will also be understood that if desired, air under pressure may be delivered to the air inlet passages and 9| of the valve base.

While I have illustrated my invention for use with fuel injected into the combustion chamber, it will be obvious that a mixture of fuel and air may be admitted at the inlet ends of the tubes, or amixture of air and gaseous fuel may be drawn into the tube in such proportion that the mixture is too lean to burn, in which combustion could be initiated by the injection of a small portion of pilot fuel into the combustion chamber in a manner well known in the gas Diesel cycle.

In place of liquid fuel, solid fuel, such as powdered coal, may be admitted into the combustion chamber and the combustion tubes can be provided with traps of any well known type to prevent the ash from being carried through the exhaust valves.

In Fig. 4, there is shown by way of example a construction by means of which powdered solid fuel may be admitted to a combustion chamber. In this figure, a portion of the apparatus shown in Fig. 1 is reproduced and the same reference characters employed in Fig. 1 are used to designate corresponding parts in Fig. 4. In this construction, the powdered solid fuel is supplied to a hopper H0 mounted on a bracket III secured to or formed integral with the air inlet duct or passage H2, which may be similar to the air inlet duct 23 shown in Fig. l. The bracket III has a slide II5 arranged therein with a vertical hole II6 therein and the slide is movable into a position to place the hole in alinement with the discharge spout of the hopper to receive powdered fuel, as shown in broken lines in Fig. 4, and into a position shown in full lines in which the fuel from the hole is discharged to a chute I I8 or passage formed in the bracket III and terminating in the air inlet passage I I2, for admission to the combustion chamber or tube I by means of the inlet valve I3. The movement of the slide II5 can, of course, be timed in accordance with the movements of the valve I3. The fluid fuel inlet nozzle II is also shown in Fig. 4, since it may be desirable to use fluid fuel, such as a gas, in connection with solid fuel.

In this construction, a trap I20 to receive ash is provided.

By means of the apparatus and method described, gases such as air and products of combustion may be compressed to any desired pressure, it being obvious that the pressure may be controlled by the amount of fuel admitted to the combustion chambers or tubes. Except for the valves, the apparatus contains no movable parts and operates at high efficiency. By introducing into the combustion chambers a quantity of air in excess of that required for combustion, the temperatures and pressures resulting from combustion of the fueliare not as high as they would be if no excess air were present and at the same time the apparatus will deliver larger volumes of compressed gas than would be the case if only sufiicient air were admitted to support combustion. This enables the apparatus to operate at lower temperatures, since the incoming scavenging air has a cooling effect on the combustion chambers. By pre-compressin the charge in each tube by means of compressed gas from another tube, the combustion chambers during ignition may operate at materially higher pressures and temperatures than in the case of combustion chambers which are not supercharged, so that rapid and complete combustion of the fuel is assured. Furthermore, by using the peaks of the pressures in the tubes for supercharging, excessive or dangerously high temperatures of the gases passing to the turbine or motor, are avoided. The combustion chambers or tubes and the valve blocks or base members may, of course, be cooled in any suitable manner, as for example by water jackets, if desired.

I claim as my invention:

1. An apparatus for delivering compressed gas to a receiver, including a stationary combustion chamber of elongated form, an air inlet valve at one end of said combustion chamber and a discharge valve at the other end thereof, means for supplying fuel and igniting the same in said combustion chamber, valve means for discharging a portion of the compressed gas from said combustion chamber to a receiver, an exhaust valve for discharging the balance of the compressed gas in said combustion chamber, and means for opening said inlet valve immediately after said exhaust valve to provide flow of incoming air into said combustion chamber due to the ballistic force of the exhaust which produces a reduction in pressure in said combustion chamber below that of the incoming air.

2. In a gas pressure generating apparatus including a combustion chamber of elongated tubular form and of substantially uniform diameter and having an air inlet valve at one end thereof and an exhaust valve at the other end thereof, means for admitting fuel to said combustion chamber and igniting the same. valve means for discharging a portion of the compressed gas from said combustion chamber to a receiver, other valve means for exhausting the balanceofthecompressedgasfromsaidtubular combustion chamber, and means for opening said I0 inlet valve when the flow of the exhaust has formed a sub-atmospheric pressure in said combustion chamber due to the ballistic force of the exhaust, to permit air to be drawn into said chamber.

3. Apparatus for delivering compressed gas to a receiver, comprising a plurality of stationary tubes each having a valve controlled inlet at one end and a valve controlled discharge at the other end, means for introducing air and fuel into said tubes at the ends thereof adjacent to said inlets, means for successively igniting said fuel in said tubes to increase the pressure of the gas in said tubes, means for conducting a portion of the compressed gas from each tube to another tube to increase the gas pressure therein before ignition takes place therein, means for conducting another portion of the compressed gas from said tubes to a receiver. means for exhausting the remaining gas from the discharge ends of said tubes, and timed valve means for admitting air during the low pressure portion of exhaust discharge for scavenging and combustion.

HANS BOHUSLAV.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 985,793 Fabel Mar. 7, 1911 1,129,544 Bischof Feb. 23, 1915 1,964,620 Cernoch June 26, 1934 2,273,406 Lasley Feb. 17, 1942 FOREIGN PATENTS Number Country Date 2,818 Great Britain Feb. 5, 1906 27,724 Great Britain of 1907 242,525 Great Britain Nov. 12, 1925 515,635 Germany Jan. 8, 1931 

